Torque Generation Mechanism and Performance Evaluation of a Dual-Sided PM Machine With Stator U-Shaped Magnets

This article proposes a new dual-sided permanent magnet (DSPM) machine with flux-concentrated U-shaped permanent magnets (PMs) in stator, and consequent-pole PMs in rotor, respectively. The proposed DSPM machine can perform a bidirectional field modulation effect (BFME) to enhance the effective harmonics, and hence improving torque capability. A magneto-motive force-permeance based model is employed to reveal the torque production mechanism. The torque contributions of main-order working field harmonics are identified and quantified by employing a hybrid finite-element (FE)/analytical method with a unified average torque equation. In order to confirm the merits of the proposed design, the basic electromagnetic characteristics of the proposed DSPM configuration are investigated and compared with those of an existing DSPM machine with stator consequent-pole PM design. Besides, in order to further reduce the cogging torque, a parallel complementary design is adopted for the final prototyping. Finally, a 6-slot/14-pole-pair prototype is manufactured, and some experimental measurements are carried out to validate the theoretical and FE analyses.